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BLF and Presence Changes from 2talk+ to Lyra

The migration from 2talk+ to Lyra changes how BLF (Busy Lamp Field) and Presence work. This article explains the change and what it means for existing setups.

When a device subscribes to BLF or Presence, it can display the state. An IP phone typically shows state using LED lights on the display. A softphone can show state in the client interface.

A BLF subscription follows the call state of the monitored device. Call states are ringing, in use, or available.

A Presence subscription follows the user state of the monitored device. User states are available, away, busy, do not disturb, and other user-set statuses.

How BLF and Presence Worked on 2talk+

  • 2talk+ treated BLF and Presence as effectively the same feature, only call state is supported
  • When an extension went on a call, 2talk+ automatically updated both BLF subscriptions and Presence subscriptions
  • Because of this, a device could subscribe to either BLF or Presence and still see line status changes such as Idle, Ringing, Busy, or On a Call
  • This behaviour occurred even where a device did not properly support Presence publishing. 2talk+ mapped call state to both subscription types regardless

How BLF and Presence Work on Lyra

Lyra follows SIP standards more closely and treats BLF and Presence as separate services

BLF (Recommended)
  • BLF subscriptions continue to show call activity, including Idle, Ringing, and In Use / Busy
  • BLF is the recommended method for monitoring extension status. Most phones and PBX systems support BLF
Presence
  • Presence subscriptions are now independent of call state
  • Presence can show user generated status information such as Available, Away, Busy, and Do Not Disturb
  • Presence requires the endpoint to support SIP Presence correctly
  • Presence requires the endpoint to actively publish its Presence state to the server
  • Other devices must subscribe to Presence state separately from BLF
  • Lyra does not automatically reflect call activity in Presence subscriptions. The device must publish that information itself

What This Means for Existing Setups

  • Most customers using BLF keys to monitor extensions will not notice any change
  • Customers who subscribe to Presence instead of BLF may see different behaviour after migrating
  • Customers with a mix of BLF subscriptions on some extensions and Presence subscriptions on others may also see different behaviour
  • In these cases, busy and idle status may not appear as expected unless the monitored device supports Presence publishing

Recommendation

Use BLF for extension monitoring wherever possible.

BLF matches the behaviour customers experienced on 2talk+ and is widely supported by IP phones and softphones.

Presence should only be used where there is a specific requirement for user controlled status, such as Available, Away, or Do Not Disturb, and where the device supports SIP Presence publishing.